We demonstrate a new material by intercalating Mo3S132− into Mg/Al layered double hydroxide (abbr. Mo3S13-LDH), exhibiting excellent capture capability for toxic Hg2+ and noble metal silver (Ag). The as-prepared Mo3S13-LDH displays ultra-high selectivity of Ag+, Hg2+ and Cu2+ in the presence of various competitive ions, with the order of Ag+>Hg2+>Cu2+>Pb2+≥Co2+, Ni2+, Zn2+, Cd2+. For Ag+ and Hg2+, extremely fast adsorption rates (≈90 % within 10 min, >99 % in 1 h) are observed. Much high selectivity is present for Ag+ and Cu2+, especially for trace amounts of Ag+ (≈1 ppm), achieving a large separation factor (SFAg/Cu) of ≈8000 at the large Cu/Ag ratio of 520. The overwhelming adsorption capacities for Ag+ (qmAg=1073 mg g−1) and Hg2+ (qmHg=594 mg g−1) place the Mo3S13-LDH at the top of performing sorbent materials. Most importantly, Mo3S13-LDH captures Ag+ via two paths: a) formation of Ag2S due to Ag-S complexation and precipitation, and b) reduction of Ag+ to metallic silver (Ag0). The Mo3S13-LDH is a promising material to extract low-grade silver from copper-rich minerals and trap highly toxic Hg2+ from polluted water.
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